Checking out a newly installed Pneumatic Elevator. It appears to use 5 vacuum pumps, in the top of the tube, to suck the cab up and down. The only power requirement is a 230v 30amp 4 wire receptacle. When in operation it does sound like a few vacuum cleaners on at the same time, definitely not silent. There was no obvious pressure change when in the cab, and it appears that if power was to fail while you are between floors, picking up the phone releases you and you slowly lower to the ground floor. For $50,000 you can have this installed in your house; all permitting, parts, and labor included. Installs in a couple days, but the process of moving wiring between floors, adding walls if your jurisdiction requires it, may increase that time significantly. The Electrical company that was used was Saltside Electric out of Pinellas County Florida.